Auto merge of rust-lang#14723 - obsgolem:master, r=Veykril

Added remove unused imports assist

This resolves the most important part of rust-lang#5131. I needed to make a couple of cosmetic changes to the search infrastructure to do this.

A few open questions:
* Should imports that don't resolve to anything be considered unused? I figured probably not, but it would be a trivial change to make if we want it.
* Is there a cleaner way to make the edits to the use list?
* Is there a cleaner way to get the list of uses that intersect the current selection?
* Is the performance acceptable? When testing this on itself, it takes a good couple seconds to perform the assist.
* Is there a way to hide the rustc diagnostics that overlap with this functionality?

Author: bors

crates/ide-assists/src/handlers/destructure_tuple_binding.rs

@@ -114,7 +114,7 @@ fn collect_data(ident_pat: IdentPat, ctx: &AssistContext<'_>) -> Option<TupleDat
     let usages = ctx.sema.to_def(&ident_pat).map(|def| {
         Definition::Local(def)
             .usages(&ctx.sema)
-            .in_scope(SearchScope::single_file(ctx.file_id()))
+            .in_scope(&SearchScope::single_file(ctx.file_id()))
             .all()
     });
 

crates/ide-assists/src/handlers/expand_glob_import.rs

@@ -120,7 +120,7 @@ fn find_parent_and_path(
 
 fn def_is_referenced_in(def: Definition, ctx: &AssistContext<'_>) -> bool {
     let search_scope = SearchScope::single_file(ctx.file_id());
-    def.usages(&ctx.sema).in_scope(search_scope).at_least_one()
+    def.usages(&ctx.sema).in_scope(&search_scope).at_least_one()
 }
 
 #[derive(Debug, Clone)]

crates/ide-assists/src/handlers/extract_function.rs

@@ -384,7 +384,7 @@ impl LocalUsages {
         Self(
             Definition::Local(var)
                 .usages(&ctx.sema)
-                .in_scope(SearchScope::single_file(ctx.file_id()))
+                .in_scope(&SearchScope::single_file(ctx.file_id()))
                 .all(),
         )
     }

crates/ide-assists/src/handlers/extract_module.rs

@@ -478,7 +478,7 @@ impl Module {
         let selection_range = ctx.selection_trimmed();
         let curr_file_id = ctx.file_id();
         let search_scope = SearchScope::single_file(curr_file_id);
-        let usage_res = def.usages(&ctx.sema).in_scope(search_scope).all();
+        let usage_res = def.usages(&ctx.sema).in_scope(&search_scope).all();
         let file = ctx.sema.parse(curr_file_id);
 
         let mut exists_inside_sel = false;

crates/ide-assists/src/handlers/inline_call.rs

@@ -80,7 +80,7 @@ pub(crate) fn inline_into_callers(acc: &mut Assists, ctx: &AssistContext<'_>) ->
 
     let is_recursive_fn = usages
         .clone()
-        .in_scope(SearchScope::file_range(FileRange {
+        .in_scope(&SearchScope::file_range(FileRange {
             file_id: def_file,
             range: func_body.syntax().text_range(),
         }))

crates/ide-assists/src/handlers/move_const_to_impl.rs

@@ -82,17 +82,19 @@ pub(crate) fn move_const_to_impl(acc: &mut Assists, ctx: &AssistContext<'_>) ->
         return None;
     }
 
-    let usages =
-        Definition::Const(def).usages(&ctx.sema).in_scope(SearchScope::file_range(FileRange {
-            file_id: ctx.file_id(),
-            range: parent_fn.syntax().text_range(),
-        }));
-
     acc.add(
         AssistId("move_const_to_impl", crate::AssistKind::RefactorRewrite),
         "Move const to impl block",
         const_.syntax().text_range(),
         |builder| {
+            let usages = Definition::Const(def)
+                .usages(&ctx.sema)
+                .in_scope(&SearchScope::file_range(FileRange {
+                    file_id: ctx.file_id(),
+                    range: parent_fn.syntax().text_range(),
+                }))
+                .all();
+
             let range_to_delete = match const_.syntax().next_sibling_or_token() {
                 Some(s) if matches!(s.kind(), SyntaxKind::WHITESPACE) => {
                     // Remove following whitespaces too.
@@ -103,7 +105,7 @@ pub(crate) fn move_const_to_impl(acc: &mut Assists, ctx: &AssistContext<'_>) ->
             builder.delete(range_to_delete);
 
             let const_ref = format!("Self::{}", name.display(ctx.db()));
-            for range in usages.all().file_ranges().map(|it| it.range) {
+            for range in usages.file_ranges().map(|it| it.range) {
                 builder.replace(range, const_ref.clone());
             }